Clinical Spectrum and Treatment Outcomes in Korean Pediatric Patients with CHD2-Related Disorders: Limited Genotype–Phenotype Correlation

Purpose: The chromodomain helicase DNA-binding (CHD) protein family comprises adenosine triphosphate-dependent chromatin remodelers that regulate chromatin structure and gene expression. Pathogenic CHD2 variants are associated with neurodevelopmental phenotypes, but these genotype–phenotype correlations remain unclear. This study aimed to delineate the clinical and genetic features of patients with CHD2-related disorders and to explore the associated genotype–phenotype relationships.Methods: Among 22 patients with pathogenic or likely pathogenic CHD2 variants identified using a customized 172-gene neurodevelopmental and epilepsy panel, 19 with sufficient clinical data were included. Demographic, clinical, neuroimaging, electroencephalographic, and genetic data were retrospectively reviewed.Results: Eighteen pathogenic or likely pathogenic variants were identified, including eight novel variants: nine nonsense (50.0%), five splice-site (27.8%), two missense (11.1%), and two exon deletions (11.1%). All patients had epilepsy, with a median age of seizure onset of 2.33 years. Comorbidities included global developmental delay (89.5%), intellectual disability (82.0%), and neuropsychiatric symptoms (47.4%). Seizure types were heterogeneous, with a predominance of generalized-onset seizures, and 13 patients (68.4%) achieved seizure freedom. Marked phenotypic variability was observed: two unrelated patients with the same truncating variant had different developmental and seizure-related profiles, a symptomatic child with an inherited exon 5 deletion contrasted with her asymptomatic father, and a patient with an exon 17–29 deletion exhibited relatively mild features.Conclusion: Epilepsy was a consistent manifestation in this study and was accompanied by diverse developmental and neurobehavioral features, with substantial genotype–phenotype discordance. Further research on genotype–phenotype correlation is warranted.